1. Technical Field
This invention is related to the field of integrated circuit implementation, and more particularly to the implementation of power supply management circuits.
2. Description of the Related Art
Computing systems may include one or more systems on a chip (SoC), which may integrate a number of different functions, such as, graphics processing, onto a single integrated circuit. With numerous functions included in a single integrated circuit, chip count may be kept low in mobile computing systems, such as tablets, for example, which may result in reduced assembly costs, and a smaller form factor for such mobile computing systems.
Since many functional blocks, such as memories, timers, serial ports, phase-locked loops (PLLs), analog-to-digital converters (ADCs) and more, may be included in an SoC, the probability that a given functional block is not in use at a given time may be high. When a functional block is not in use, the SoC may turn the block off by disabling power to it to conserve power, to reduce the internal chip operating temperature, and the like. However, when the functional block is needed again, power must be turned back on and the block must be initialized. Any data or operational settings stored in the functional block are lost when power is disabled.
In some SoC designs, functional blocks that are not used all of the time may be placed into a retention mode. In a retention mode, clock signals to the functional block may be disabled and the power supply to the block may be reduced to a level that allows the block to retain some or all of the operational settings and/or data contained within the block. This may allow some power savings or temperature reduction without a functional block requiring to be re-initialized when it is needed again. In order to implement a retention mode, a power supply with a voltage level below the main system operating voltage may be required. In addition, it is desirable to implement this power supply with minimal impact to the total chip power consumption.
Power regulation circuits may be designed in accordance with various designs styles including passive and active designs. Passive regulating circuits may employ a voltage drop across a passive circuit element such as, e.g., a resistor or a diode, to generate a voltage level below the main system operating voltage.
The flexibility to control the voltage output may be provided by using active power regulating circuits. Active power regulating circuits allow control over the voltage output by monitoring the output and comparing the output to one or more known voltage references. The output may be adjusted higher or lower based on this comparison.